Jenson Button believes it will be hard for anyone bar Sebastian Vettel to catch Fernando Alonso in the title race.

Vettel is Alonso's nearest competitor, 29 points adrift, while a retirement for Button's McLaren team-mate Lewis Hamilton at the Singapore Grand Prix saw him drop to fourth, 52 points off the lead and behind Kimi Raikkonen in third. Based on the performances at the last four races, McLaren has the fastest car, but Button, who is 75 points off Alonso, thinks challenging for the title will be a long shot.

"It's hard for anyone [to catch Alonso] except Seb at the moment," Button was quoted by BBC Sport. "It's between those two but there's still a lot of people with a long shot. That's what we're all going to go for."

"It just shows one bad race makes a massive difference," he added. "Fernando had his in Spa, Lewis had his in Spa and here, Seb had his at the last race. I had mine in the last race. When no-one has the consistency you can't close a big gap on someone. Seb is only 29 points behind, that's a gap that's shrinking."

Button is also concerned about McLaren's reliability after he retired from the Italian Grand Prix with a fuel pick-up problem and Hamilton pulled out of the lead of the Singapore Grand Prix with a gearbox failure.

"It's disappointing for the team to have another DNF - two weekends on the trot," he said. "It's something that we need to sort out because as a team over the race weekends we're doing a great job and the pace is there with the car. Over the last few races the results we've had have been very good but it's just we can't seem to do that with both cars. It's something for sure we need to work on for the rest of the season."